There are a variety of approaches for forming particles from flowable masses. Often the flowable mass is a melt. Melts are commonly prepared by providing one or more raw materials in a molten form into a batch mixer. The mixer is sized and dimensioned to provide for a desired residence time for the raw material or materials in the mixer to sufficiently mix and or react the raw material or materials and provide a uniform temperature to the melt. After exiting the batch mixer, the melt can optionally be passed through one or more filters to remove deleterious matter. The melt can then be fed into a feed pump that moves the melt via a feed pipe from the feed pump to the apparatus that dispenses the melt to form particles.
One approach available for dispensing the melt to form particles is rotoforming. In a typical rotoforming process, the melt is transported through the feed pipe to a stator. A cylinder having a plurality of apertures is rotated about the stator and the apertures intermittently are in fluid communication with the stator. The melt is dispensed form the apertures in registration with stator and deposited on a moving conveyor having a flat surface. The melt is cooled on the conveyor to form a plurality of particles.
The shapes of particles that can be generated by depositing the precursor material onto a flat conveyor are generally limited to particles having a flat surface. The flat surface of the particle tends to correspond with the flat surface of the conveyor upon which the particle rests when formed. Depending on the rheological and wetting properties of the melt, the particles may be dome shaped. That is the particles may have one generally flat surface and the remainder of the surface may be a curved surface.
Dome shaped particles, when poured into a container, can tend to pack in a container less efficiently than particles having a shape that tends towards more spherical. When dome shaped particles having a flat surface are poured into a container, the packing of the particles is likely to be less than optimum. Thus, the mass of such particles that can be contained in a container of a particular volume tends to be lower than what could be obtained if the packing was optimum regardless of shape of the particles or if the particles had some other shape that is optimal for packing. Optimal packing can be preferred because it can provide for consistent fill levels amongst containers having the same shape and fill weight.
With these limitations in mind, there is a continuing unaddressed need for apparatuses and processes for forming particles that can be packed into containers efficiently.